Cutting tools have been provided with wear resistance by forming a hard coating of TiN, TiCN, TiAlN, or the like on a substrate of high speed steel, cemented carbide, cermet, and the like. In particular, TiAlN has been the favorable choice in the case of the coating formed on a high speed cutting tool or a hardened cutting tool of, for example, hardened steel. With the recent increase in the hardness of the material to be cut by the cutting tool and increase in the cutting speed, development of a hard coating having an improved wear resistance is highly demanded. JP-A No. 2003-71610, for example, discloses that use of TiCrAlN instead of the TiAlN increases proportion of the AlN having rock-salt structure in the coating, and the coating hardness is thereby improved simultaneously with oxidation resistance.
The hard coating comprising TiAlN or TiCrAlN, however, is insufficient in lubricity in spite of the improved oxidation resistance at the high temperature. Accordingly, cutting tools having such hard coating formed thereon often suffered from sticking of a part of the work piece onto the surface of the cutting tool during the cutting operation. Jigs and tools such as forging dye and blanking punch also suffered from unduly increased frictional resistance at the contact surface, and they occasionally experienced baking of the processed material onto the jig or the tool during the forging and pressing.